A location of a computing device can be estimated based on Global Positioning System (GPS) signals. For example, a mobile computing device may receive GPS signals and responsively estimate the device location on the face of the Earth (e.g. an absolute location expressed by latitude and longitude values). Generally, there are various factors that influence the accuracy of estimated locations based on GPS signals. These factors may include the number of usable GPS signals from different GPS satellites or sources, the positions of GPS satellites or sources, atmospheric conditions that affect GPS signals, physical barriers (such as mountains, manmade structures, trees, and the like) that may interfere with GPS signals, movement of the computing device while GPS signals are being received and/or while the device is estimating the location, among other factors.
In addition using GPS signals to estimate a latitudinal and longitudinal location of a device, GPS signals can also be used to provide elevation or altitude estimates. However, such elevation estimates may have a horizontal or vertical error of within about plus or minus fifteen meters (plus or minus about fifty feet). Thus, elevation estimates using GPS signals may not be sufficiently accurate to provide useful or reliable information for some applications of the computing device. For instance, elevation estimates using GPS signals may not be sufficiently accurate to provide a reliable estimate of which floor the computing device is located within a multi-story building.
Generally, it is desirable to improve on the arrangements of conventional methods and systems or at least to provide one or more useful alternatives to help to make localization of a computing device more efficient, reliable, and/or accurate.